Locating a Tubing Leak - George E King Petroleum Engineering Oil ...

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Problem orInformationNeededLocation of leakto annulus orcrossflow behindpipeLocation of Source of Annular LeakRec. Logging Tools Procedure / Level of DetailTemperaturesurveyNoise logOxygen activationlogBorax LogRelatively accurate at rates of at 1 bpd or more. Needminimum of 2 runs, before and during injection. A thirdrun may help define a qualitative level of leak rate. Runat 1 o F/in sensitivity. Will not see small gas leak ratesthrough liquid.Best for gas leak detection. Run static log and then againduring flow or negative test. Upward gas movement(percolation) at actual 10 ft3/D or more should bedetectable.Can detect flows of 20 to 40 bpd in the annulus of asingle string well if the leak is directly opposite the tool.Resolution drops to >200 bpd when two strings arepresentPumping borax/water solution down tbg into the liner,allowing mix to invade perfs & any channels incasing/formation annuli. Initial pass, before borateinjection, is w/ Pulsed Neutron log (no Borax), followedby passes at 20bbls, 40bbls, and 60bbls as borax mixpumped. Borax affects neutron capture, leaving acharacteristic signature. Overlays of the Sigma/CNLcounts reveal the zones of borax penetration, andidentifies channels taking fluid.George E. King Engineering3/14/2009 10GEKEngineering.com
Channel Detection Behind Pipe• Channel logging, with borax solution injection, isaccomplished by pumping the solution down the tubing intothe liner, allowing the mix to infiltrate the perforations andany channels in the casing formation annuli.• The initial pass, before borate injection, is made with a thrutubingPulsed Neutron logging (or memory neutron) base pass(no Borax), followed by subsequent passes at 20bbls, 40bbls,and 60bbls as the borax solution is pumped away.• The borax affects neutron capture, leaving a characteristicsignature. Overlays of the Sigma/CNL counts reveal the zonesof borax penetration, and identify the channels taking fluid.3/14/2009 11George E. King EngineeringGEKEngineering.com
Page 1 and 2: Locating a Tubing Leak• High reso
Page 3: Location of Cement TopProblem orInf
Page 6 and 7: Determination of External Casing Co
Page 8 and 9: Problem orInformationNeededDetermin
Page 12: Comparison of a memory CNL and PNL

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